LAUSR

The purpose of this study was to compare zinc sulfate and zinc threonine chelate based on Zn bioavailability and performance of broiler chicks. The study was conducted in a completely randomized design with 256 day-old Ross 308 chicks and eight treatments including control treatment (no zinc supplementation), three levels of zinc sulfate and zinc threonine chelate (40, 80, and 120 mg zinc per kg feed), and a common commercial chelate (Bioplex Zn®) supply 40 mg zinc per kg feed. The results of total period showed that threonine chelate group had the highest live weight compared with other treatments and lowest feed conversion ratio belonged to 80 and 120 ppm of zinc threonine chelate (p < 0.05). Zinc threonine chelate and commercial chelate treatments had the lowest cholesterol and LDL levels compared with other treatments (p < 0.05). Zinc chelate threonine which contains 80 and 120 ppm of zinc had the highest HDL and superoxide dismutase enzymes and the lowest heterophile to lymphocyte ratio compared with other treatments (p < 0.05). Relative bioavailability of zinc threonine to zinc sulfate based on body weight, feed conversion ratio, cholesterol, LDL, HDL, superoxide dismutase enzyme, ash, and zinc content in tibia were 418.75, 173.91, 131.38, 159.43, 278.63, 193.45, 156.46, and 117.65%, respectively. According to the results of broiler performance and other traits measured in this study, it seems that the use of 80 ppm of zinc threonine chelate in the broiler diet is recommended in comparison with zinc sulfate levels and other threonine chelate levels.